Addendum to “Stöffler,D., Hamann,C., and Metzler,K., Shock metamorphism of planetary silicate rocks and sediments: Proposal for an updated classification system. Meteoritics & Planetary Science 53, 5–49, 2018”     

Dieter Stffler  Christopher Hamann  Knut Metzler 《Meteoritics & planetary science》2019,54(4):946-949

With this addendum we provide some correction and additional information regarding the above cited publication. It addresses the following two topics. (1) Clarification for a correct application of the criteria for certain shock stages of chondrites, in particular stage C‐S6. (2) Correction of a printing error in the table that contains the shock classification system of chondrites.  相似文献   

Investigation of the thermal history of the Delaware Basin (West Texas,USA) using carbonate clumped isotope thermometry     

H. Nathan Naylor  William F. Defliese  Ethan L. Grossman  Christopher R. Maupin 《Basin Research》2020,32(5):1140-1155

We utilized carbonate clumped isotope thermometry to explore the thermal history of the Delaware Basin, West Texas, USA. Carbonate wellbore cuttings from five oil/gas wells across the basin yielded clumped isotope temperatures (T(Δ₄₇)) ranging from 27°C to 307°C, interpreted to reflect a combination of initial precipitation/recrystallization temperature and solid-state C-O bond reordering during burial. Dolomite samples generally record lower apparent T(Δ₄₇)s than calcite, reflecting greater resistance to reordering in dolomite. In all five wells, clumped isotope temperatures exceed modern downhole temperature measurements, indicating higher heat flow in the past. Using modelled burial curves based on sedimentological history, we created unique time-temperature histories by linearly applying a geothermal gradient. Applying two different thermal history reordering models, we modelled the extent of solid-state C–O bond reordering to iteratively find the time-averaged best-fit geothermal gradients for each of the five wells. Results of this modelling suggest that the shallower, southwestern portion of the study area experienced higher geothermal gradients throughout the sediment history (~45°C/km) than did the deeper, southeastern portion (~32°C/km), with the northern portion experiencing intermediate geothermal gradients (~35–38°C/km). This trend is in agreement with the observed gas/oil ratios of the Delaware Basin, increasing from east to west. Furthermore, our clumped isotope temperatures agree well with previously published vitrinite reflectance data, confirming previous observations and demonstrating the utility of carbonate clumped isotope thermometry to reconstruct basin thermal histories.  相似文献   

Influence of land-use change on near-surface hydrological processes: Undisturbed forest to pasture     

Sonja Germer  Christopher Neill  Alex V. Krusche  Helmut Elsenbeer 《Journal of Hydrology》2010,380(3-4):473-480

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The M/V Cosco Busan spill: source identification and short-term fate   总被引：1，自引：0，他引：1  

Lemkau KL  Peacock EE  Nelson RK  Ventura GT  Kovecses JL  Reddy CM 《Marine pollution bulletin》2010,60(11):2123-2129

Understanding the fate of heavy fuel oils (HFOs) in the environment is critical for sound decisions regarding its usage and spill cleanup. To study weathering of HFOs, we examined the M/V CoscoBusan spill (November 2007; San Francisco Bay, CA, USA). In this baseline report, we identified which ruptured tank (port tank 3 or 4) was the source of the spilled oil and characterized changes in the oil composition across location and time. Samples from three impacted shorelines, collected within 80 days of the spill, were analyzed using one- and two-dimensional gas chromatography (GC and GC × GC, respectively). Weathering varied across sites, but compounds with GC retention times less than n-C₁₆ were generally lost by evaporation and dissolution. Changes in n-C₁₈/phytane and benz[a]anthracene/chrysene ratios indicated some biodegradation and photodegradation, respectively.  相似文献   

Processes controlling rapid temperature variations on rock surfaces     

Jamie L. Molaro  Christopher P. McKay 《地球表面变化过程与地形》2010,35(5):501-507

In arid environments, thermal oscillations are an important source of rock weathering. Measurements of temperature have been made on the surface of rocks in a desert environment at a sampling interval of 0·375 s, with simultaneous measurements of wind speed, air temperature, and incoming shortwave radiation. Over timescales of hours, the temperature of the rock surface was determined primarily by shortwave radiation and air temperature, while rapid temperature variations, high dT/dt, at intervals of seconds or less, were determined by wind speed. The maximum values of temperature change and time spent above 2°C min^?1 increased at high measurement rates and were much higher than previously reported. The maximum recorded value of dT/dt was 137°C min^?1 and the average percentage time spent above 2°C min^?1 was ～70 ± 13%. Maximum values of dT/dt did not correlate with the maximum values of time spent above 2°C min^?1. Simultaneous measurements of two thermocouples 5·5 cm apart on a single rock surface had similar temperature and dT/dt values, but were not correlated at sampling intervals of less than 10 s. It is suggested that this is resulting from rapid fluctuations due to small spatial and timescale wind effects that are averaged out when data is taken at longer sampling intervals, ～10 s or greater. Published in 2010 by John Wiley & Sons, Ltd.  相似文献   

Endemic avifaunal biodiversity and tropical forest loss in Makira, a mountainous Pacific island     

Finn Danielsen  Christopher E. Filardi  Knud A. Jønsson  Victor Kohaia  Niels Krabbe  Jan B. Kristensen  Robert G. Moyle  Patrick Pikacha  Michael K. Poulsen  Mikael K. Sørensen  Charles Tatahu  Joseph Waihuru  Jon Fjeldså 《Singapore journal of tropical geography》2010,31(1):100-114

Anthropogenic habitat changes and the introduction of pigs, dogs, cats and rats have caused a catastrophic decline in the terrestrial biodiversity of Pacific archipelagos. At present, economic globalization and an increased demand for timber are promoting industrial logging and plantation expansion. Commercial logging can be sustainable but in practice it more often leads to land degradation, especially on small flat islands. On large and mountainous islands, however, more modest impacts can be expected as the narrowly endemic species tend to inhabit montane forests where logging is difficult. In this study we use ornithological data collected at different elevations to assess the extent to which the avifauna of Makira, a large mountainous island in Melanesia, will be affected by deforestation of the lowlands, most of which are under timber concessions. Our data suggest that a majority of the endemic bird species use lowland forest to some extent and that this may even apply to species hitherto associated with montane forest. If current commercial forestry programmes are continued, the forest habitat may be disturbed or lost over large parts of Makira, potentially undermining the natural resource base for the local subsistence economy, exacerbating climate change and threatening the integrity of one of the most important areas for biodiversity conservation on earth. Our study highlights the importance of understanding the habitat requirements of endemic species and the urgency of establishing and effectively managing community-based protected areas in suitable lowland forests of the Pacific.  相似文献   

Barrier‐spit geomorphology and inlet dynamics in absence of tides: evolution of the North Pond system,eastern Lake Ontario,New York State          下载免费PDF全文

Christopher R. Mattheus  Joshua K. Fowler  Thomas P. Diggins  Derrick F. Allen 《地球表面变化过程与地形》2016,41(10):1386-1398

Barrier systems have received much attention along microtidal oceanic coastlines, where countless studies discuss their evolution in response to Holocene sea‐level rise, storm influence, and anthropogenic impacts. Lacustrine barrier evolution is not as well investigated and little is known about how lake‐specific hydrodynamic processes shape barrier morphology. This study evaluates the evolution of a highly dynamic barrier section along eastern Lake Ontario in the context of varying water levels and winter‐ice covers. Paleoshoreline reconstructions and volumetric analyses of nearshore sedimentation indicate the central portion of the studied North Pond barrier has been breached many times in different locations throughout the last century. Ground‐penetrating radar (GPR) data corroborate mapped locations of former inlets, bound at the surface by recurved spit and dune ridges. Subsurface structural controls on inlet position are inferred from a spatial correlation with buried incised fluvial channels, formed during a Holocene lake‐level lowstand. While subsurface controls caused two separate historical inlets to remain stationary while open, an episode of rapid inlet migration elsewhere along the barrier was facilitated by the prevailing direction of coastal currents and high lake levels, which favored overwash and rapid longshore sediment mobility across a low‐gradient barrier section. Additionally, the sudden closing of an inlet after many decades of operation coincidental with the opening of another suggestively occurred alongside unusually high lake levels. These correlations suggest the degree of coastal inundation, predominantly a function of fluctuating lake levels and antecedent topography, represent strong controls on overall barrier geomorphology over decadal timescales. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

Precursors to dyke-fed eruptions at basaltic volcanoes: insights from patterns of volcano-tectonic seismicity at Kilauea volcano,Hawaii   总被引：2，自引：2，他引：0  

Andrew F. Bell  Christopher R. J. Kilburn 《Bulletin of Volcanology》2012,74(2):325-339

To investigate the physical controls on volcano-tectonic (VT) precursors to eruptions and intrusions at basaltic volcanoes, we have analyzed the spatial and temporal patterns of VT earthquakes associated with 34 eruptions and 23 dyke intrusions that occurred between 1960 and 1983 at Kilauea, in Hawaii. Eighteen of the 57 magmatic events were preceded by an acceleration of the mean rate of VT earthquakes located close to the main shallow magma reservoir. Using a maximum-likelihood technique and the Bayesian Information Criterion for model preference, we demonstrate that an exponential acceleration is preferred over a power-law acceleration for all sequences. These sequences evolve over time-scales of weeks to months and are consistent with theoretical models for the approach to volcanic eruptions based on the growth of a population of fractures in response to an excess magma pressure. Among the remaining 40 magmatic events, we found a significant correlation between swarms of VT earthquakes located in the mobile south-flank of Kilauea and eruptions and intrusions. The behaviour of these swarms suggests that at least some of the magmatic events are triggered by transient episodes of elevated rates of aseismic flank movement, which could explain why many eruptions and intrusions are not preceded by longer-term precursory signals. In none of the 57 cases could a precursory sequence be used to distinguish between the approach to an eruption or an intrusion, so that, even when a precursory sequence is recognized, there remains an empirical chance of about 40% (24 intrusions from 57 magmatic events) of issuing a false alarm for an imminent eruption.  相似文献   

Source Screening Module for Contaminant Transport Analysis Through Vadose and Saturated Zones     

Vivek Bedekar  Christopher Neville  Matthew Tonkin 《Ground water》2012,50(6):954-958

At complex sites there may be many potential sources of contaminants within the vadose zone. Screening‐level analyses are useful to identify which potential source areas should be the focus of detailed investigation and analysis. A source screening module (SSM) has been developed to support preliminary evaluation of the threat posed by vadose zone waste sites on groundwater quality. This tool implements analytical solutions to simulate contaminant transport through the unsaturated and saturated zones to predict time‐varying concentrations at potential groundwater receptors. The SSM integrates several transport processes in a single simulation that is implemented within a user‐friendly, Microsoft Excel? ‐ based interface.  相似文献   

On the behaviour of dynamic contributing areas and flood frequency curves in North American Prairie watersheds     

Eghbal Ehsanzadeh  Christopher Spence  Garth van der Kamp  Brian McConkey 《Journal of Hydrology》2012

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